BOULDER, Colo. (AP) - The Boulder sheriff’s office says two more possibly poisonous meatballs have been found in a Gunbarrel park popular with dog owners.

In a statement Sunday, the sheriff’s office said it appeared the meatballs had been placed at the park north of Boulder at the same time as others previously discovered.

The sheriff’s office says a $4,500 reward has been offered for information leading to the arrest and conviction of whoever is responsible. Pet owners are urged to watch what their animals eat in the area.

Authorities had previously recovered eight meatballs laced with rat poison from the park, and veterinarians are monitoring three dogs.